A last-resort if PreCheck fails and you're really desperate: you can join CLEAR on-the-spot and use that to go through. It's nearly $200, but it does last for a year.

I used to have CLEAR, but I experimented with dropping it, knowing that I could always rejoin CLEAR at the airport if I wanted. So far, it's been a year, and I've gotten PreCheck for every single flight (maybe 50 flights), and the lines have been reasonable, so I still haven't needed CLEAR.